CRAs for use in Corrosive Environments
Corrosion Resistant Alloys for Use in Corrosive Environments
Corrosion is around us, it is inevitable, and could be costly. CRAs are designed to resist degradation in the environment and media in which they are deployed. Usually, the choice to use a CRA means some capital expenditure higher than usual will be incurred; hence, the reason to be sure what CRA is been used in any application. Interestingly, there are many CRAs and also a myriad of applications to deploy them – no one CRA is a silver bullet.
So what are the effects of the environment on a CRA and what are the implications? This is mainly localised corrosion (pitting and crevice corrosion) and cracking, and its implications are usually economic, health, safety and environment, physical collateral damage, and/or corporate reputational issues altogether.
Now, to avoid/minimise these issues, the right CRA must be used in any particular application. Material selection criteria usually revolve around the pitting resistance equivalent number (PREn), Iso-corrosion curve data, and experience. Cost, application requirement, availability, material properties and weldability are factors that affect material selection decision making. Performance is service will largely be affected by the alloy type, design and quality of fabrication. Overall, a competent and experienced hand cannot be ignored.
The fact is that corrosion cost are real, potential problems can be better managed, corrosion can be controlled and expert advice does save money in the long run.